<!DOCTYPE html>
<html lang="en">
<head>
    <!--<meta charset="UTF-8">-->
    <title>展开与收起效果演示</title>
</head>
<style>
    body{
        margin:  0px auto;
        padding: 0px;
    }
    #pn{
        background: #e8e8e8;
        width: 600px;
        margin-left: 350px;
        height:auto;
        text-align: center;
        padding: 5px;
        display: block;
    }
    .cn{
        margin-left: 350px;
        padding:5px;
        width: 600px;
        background: gray;
        text-align: center;
        height:40px;
        color: #FFF;
    }

</style>
<body>
<div id="pn">
    <h1>欢迎来到慕课网</h1>
    <h2>大幅的广告</h2>
</div>
<div class="cn">
慕课网欢迎您<br />
    正文
</div>
</body>
</html>